Electric protective switching devices are known, especially as motor starters or motor circuit breakers, whose control electronics can be connected via a communication bus (for example, German patent applications DE 19820667 A1, DE 19924413 A1, DE 10010290 A1).
Other protective switching devices comprise essentially a base module, a manual actuation device, an electronic control unit, an actuator unit and a trigger. At least the switching mechanism is actuated with a manual actuation device via a knob and via an actuating shaft, whereby the actuating device is accommodated in a housing part that projects towards the front panel, and the actuating shaft is arranged perpendicular to the front panel. The knob protrudes from the front panel and can preferably be configured so that it can also be locked.
Examples of modular protective switching devices that are structured according to the modular principle have been described in German patent application DE 3642719 A1 or in international patent application WO 01-27958 A1. Another motor circuit breaker can also be fitted with a replaceable overcurrent release module (Swiss patent specification CH-PS 319019).
German patent application DE 195 15 923 A1 describes a protective switching device that can be expanded modularly by plugging in replaceable supplementary modules. The protective switching device has a prismatic housing part extending towards the front panel and, on this housing part, two connection surfaces and contact surfaces are formed perpendicular to the front panel. In this prior art, the supplementary modules can be plugged directly onto the protective switching device or else they are attached onto a substrate (support rail) separately from the protective switching device.
European patent specification EP 0843332 B1 describes a power breaker with a removable communication module.